Method and apparatus for metering catalyst in a fluid catalytic cracking catalyst injection system

ABSTRACT

A method and apparatus for metering catalyst in a fluid catalytic cracking catalyst injection system are provided. In one embodiment, apparatus for metering catalyst in a fluid catalytic cracking catalyst injection system includes a low pressure storage vessel coupled to a pressure vessel that defines a high pressure side of the apparatus, where the determination of the amount of catalyst transferred is made on the low pressure side of the apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/168,685 filed Jun. 28, 2005 which is a divisional of U.S. patentapplication Ser. No. 10/374,450, filed Feb. 26, 2003, now U.S. patentSer. No. 6,974,559 issued Jan. 13, 2005 both of which are herebyincorporated by reference in their entireties. This application isrelated to U.S. patent application Ser. No. 11/276,899, filed Mar. 17,2006, entitled “Multi-Catalyst Injection System” by Evans and U.S.patent application Ser. No. 11/267,903, filed Mar. 17, 2006, entitled“Mobile Fluid Catalytic Cracking Injection System” by Evans both ofwhich are hereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to a method and apparatusfor metering catalyst in a fluid catalytic cracking catalyst injectionsystem and the like.

2. Description of the Related Art

FIG. 1 is a simplified schematic of one embodiment of a conventionalfluid catalytic cracking system 130. The fluid catalytic cracking system130 includes a fluid catalytic cracking (FCC) unit 110 coupled to acatalyst injection system 100, an oil feed stock source 104, an exhaustsystem 114 and a distillation system 116. One or more catalysts from thecatalyst injection system 100 and oil from the oil feed stock source 104are delivered to the FCC unit 110. The oil and catalysts are combined toproduce an oil vapor that is collected and separated into variouspetrochemical products in the distillation system 116. The exhaustsystem 114 is coupled to the FCC unit 110 and is adapted to controland/or monitor the exhausted byproducts of the fluid cracking process.

The catalyst injection system 100 may include a main catalyst injector102 and one or more additive injectors 106. The main catalyst injector102 and the additive injector 106 are coupled to the FCC unit 110 by aprocess line 122. A fluid source, such as a blower or air compressor108, is coupled to the process line 122 and provides pressurized fluid,such as air, that is utilized to carry the various powdered catalystsfrom the injectors 102, 106 through the process line 122 where they arecombined with oil from the oil feed stock source 104 and delivered intothe FCC unit 110.

FIG. 2 is one embodiment of a conventional additive injector 106. Theadditive injector 106 includes a pressure vessel 220 and a low pressurestorage vessel 240. The pressure vessel 220 is coupled to one or moreload cells 210 for weighing the catalyst that will be introduced intothe FCC unit 110 through the process line 122. In operation, thecatalyst is dispensed into the pressure vessel 220 at atmosphericpressure from the low pressure storage vessel 240. The pressure vessel220 is subsequently weighed to determine the amount of catalyst loadedtherein. The pressure vessel 220 is then pressurized by a pressurecontrol device 228 coupled to the vessel 220 to a level that facilitatesmovement of the pressurized catalyst into process line 122 and then intothe FCC unit 110. If the pressure vessel 220 is supported by any of thestructural components surrounding it, other than the load cells 210(such as pipes, electrical conduits, and the like), those componentswill prevent the load cells 210 from accurately measuring the weight ofcatalyst added to the pressure vessel 220, and ultimately into the FCCunit 100. Therefore, in order to obtain a reasonably accurate measure ofthe catalyst, the pressure vessel 220 must not be supported by othercomponents of the system.

To isolate the pressure vessel 220 from the components coupled thereto,flexible connectors, such as bellows 230, are used to couple thepressure vessel 220 to the low pressure vessel 240, the process line122, and other surrounding components. The bellows 230 allow thepressure vessel 220 to “float” on the load cells 210 so a more accuratereading may be obtained. However, use of flexible bellows 230 does notreliably insure accurate weight measurement of the pressure vessel 220.For example, the weight of the pressure vessel 220 is still slightlysupported by the flexible bellows 230—a problem compounded by the factthat a plurality of bellows 230 must be utilized to isolate the pressurevessel 220 from the various components coupled thereto. Therefore, thedetermination of the weight of the catalyst added to the pressure vessel220 is still not accurate. Moreover, due to the operating pressures andpotentially explosive atmosphere, bellows meeting operational standardsare quite expensive and wear quickly, resulting in the drift of weightreadings, catalyst dust leaks and associated environmental issues, aswell as necessitating costly process downtime and bellows replacement.

FIG. 3 is another embodiment of an additive injector 300. The injector300 includes a high pressure storage vessel 340 coupled by a meteringvalve 330 to the process line 122. The metering valve 330 may beactuated to allow a predefined amount of catalyst to be introduced intothe process line 122 and combine with the oil from the oil feed stocksource 104 before entering the FCC unit 110. The high pressure storagevessel 340 contains a bulk supply of catalyst, for example, from about 1to about 20 tons of catalyst, and is maintained at a pressure betweenabout 50 to about 60 pounds per square inch (psi) by a pressure controldevice 320. As such, the pressure vessel 340 is subject to regulatoryconstruction standards which cause the vessel to be relatively expensiveas compared to a comparably sized, low pressure storage vessel. The highpressure vessel 340 is coupled to a plurality of load cells 310 whichenable the weight of the high pressure storage vessel 340 to bedetermined. The weight of the catalyst injected is determined bycomparing the weight of the high pressure storage vessel 340 before andafter catalyst injection.

Metering catalyst in the manner described with reference to FIG. 3eliminates the need for bellows used to isolate the pressure vessel.However, large high pressure storage vessels are very expensive.Therefore, there is a need for a method and apparatus for meteringcatalyst in a fluid catalytic cracking catalyst injection system thatminimizes the cost of ownership.

SUMMARY OF THE INVENTION

A method and apparatus for metering catalyst in a fluid catalyticcracking catalyst injection system are provided. In one embodiment,apparatus for metering catalyst in a fluid catalytic cracking catalystinjection system includes a low pressure storage vessel coupled to apressure vessel that defines a high pressure side of the apparatus wherethe determination of the amount of catalyst transferred is made on thelow pressure side of the apparatus.

DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 is a simplified schematic view of a conventional fluid catalyticcracking system;

FIG. 2 is a simplified elevation view of one embodiment of aconventional catalyst injector having a low pressure storage vessel;

FIG. 3 is a simplified elevation view of another embodiment of aconventional catalyst injector having a high pressure storage vessel;

FIG. 4 is a simplified elevation view of a fluid catalytic crackingsystem illustrating a catalyst metering system in accordance with oneembodiment of the present invention;

FIG. 5 is a simplified elevation view of a fluid catalytic crackingsystem illustrating a catalyst metering system in accordance withanother embodiment of the present invention;

FIG. 6 is a flow diagram representing an inventive method for meteringcatalyst in a fluid catalytic cracking system;

FIG. 7 is a simplified elevation view of a fluid catalytic crackingsystem illustrating a catalyst metering system in accordance withanother embodiment of the invention; and

FIG. 8 is a simplified elevation view of a fluid catalytic crackingsystem illustrating a catalyst metering system in accordance withanother embodiment of the present invention.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the figures.

DETAILED DESCRIPTION

FIG. 4 depicts one embodiment of a fluid catalytic cracking (FCC) system400 comprising an injection system 402 and oil feed stock source 450coupled to an FCC unit 424. The FCC unit 424 is adapted to promotecatalytic cracking of petroleum feed stock provided from the source 450and may be configured in a conventional manner. The injection system 402is coupled to the FCC unit 424 and is configured to inject one or morecatalysts into the FCC unit 424 to control processing attributes such asthe ratio of products recovered in a distiller of the FCC unit 424and/or to control the emissions from the FCC unit 424. The injectionsystem 402 includes a control module 404 to control the rates and/oramounts of catalyst provided to the FCC unit 424 by the injection system402.

The control module 404 has a central processing unit (CPU) 460, memory462, and support circuits 464. The CPU 460 may be one of any form ofcomputer processor that can be used in an industrial setting forcontrolling various chambers and subprocessors. The memory 462 iscoupled to the CPU 460. The memory 462, or computer-readable medium, maybe one or more of readily available memory such as random access memory(RAM), read only memory (ROM), floppy disk, hard disk, or any other formof digital storage, local or remote. The support circuits 464 arecoupled to the CPU 460 for supporting the processor in a conventionalmanner. These circuits include cache, power supplies, clock circuits,input/output circuitry, subsystems, and the like. In one embodiment, thecontrol module 404 is a programmable logic controller (PLC), such asthose available from GE Fanuc. However, from the disclosure herein,those skilled in the art will realize that other control modules such asmicrocontrollers, microprocessors, programmable gate arrays, andapplication specific integrated circuits (ASICs) may be used to performthe controlling functions of the control module 404. One control module404 that may be adapted to benefit from the invention is described inthe previously incorporated U.S. patent applications Ser. Nos.10/304,670 and 10/320,064.

In one embodiment, the injection system 402 includes a storage vessel440 coupled to a metering device 408. The metering device 408 is coupledto the control module 404 so that an amount of catalyst delivered to theFCC unit 424 may be monitored and/or metered. The storage vessel 440 isa container adapted to store catalyst therein at substantiallyatmospheric pressures and has an operational pressure of between aboutzero to about 30 pounds per square inch. The storage vessel 440 has afill port 442 and a discharge port 434. The discharge port 434 istypically positioned at or near a bottom of the storage vessel 440.

The metering device 408 is coupled to the discharge port 434 to controlthe amount of catalyst transferred from the storage vessel 440 to thepressure vessel 420 through a catalyst delivery line 414. The meteringdevice 408 may be a shut-off valve, rotary valve, mass flow controller,pressure vessel, flow sensor, positive displacement pump, or otherdevice suitable for regulating the amount of catalyst dispensed from thestorage vessel 440 into the pressure vessel 420 for injection into theFCC unit 424. The metering device 408 may determine the amount ofcatalyst supplied by weight, volume, time of dispense, or by othermeans. Depending on the catalyst requirements of the FCC system 400, themetering device 408 may be configured to provide from about 5 to about4000 pounds per day of additive-type catalysts (process controlcatalyst) or may be configured to provide from about 1 to about 20 tonsper day of main catalyst. The metering device 408 typically deliverscatalysts over the course of a planned production cycle, typically 24hours, in multiple shots of predetermined amounts spaced over theproduction cycle. However, catalysts may also be added in an “as needed”basis. In the embodiment depicted in FIG. 4, the metering device 408 isa control valve 432 that regulates the amount of catalyst delivered fromthe storage vessel 440 to the FCC unit 424 by a timed actuation. Controlvalves suitable for use as a metering device are available from InterCatEquipment Inc., located in Sea Girt, N.J.

The injection system 402 may also include one or more sensors forproviding a metric suitable for determining the amount of catalystpassing through the metering device 408 during each transfer of catalystto the pressure vessel 420. The sensors may be configured to detect thelevel (i.e., volume) of catalyst in the storage vessel 440, the weightof catalyst in the storage vessel 440, the rate of catalyst movementthrough the storage vessel 440, discharge port 434, metering device 408,and/or catalyst delivery line 414, or the like.

In the embodiment depicted in FIG. 4, the sensor is a plurality of loadcells 410 adapted to provide a metric indicative of the weight ofcatalyst in the storage vessel 440. The load cells 410 are respectivelycoupled to a plurality of legs 438 that support the storage vessel 440above a mounting surface 430. Each of the legs 438 has one of theplurality of load cells 410 coupled thereto. From sequential datasamples obtained from the load cells 410, the control module 404 mayresolve the net amount of transferred catalyst after each actuation ofthe metering device 408 (e.g., the control valve 432). Additionally, thecumulative amount of catalyst dispensed over the course of theproduction cycle may be monitored so that variations in the amount ofcatalyst dispensed in each individual cycle may be compensated for byadjusting the delivery attributes of the metering device 408, forexample, by changing the open time of the control valve 432 to allowmore (or less) catalyst to pass therethrough and into the pressurevessel 420 for ultimate injection into the FCC unit 424.

Alternatively, the sensor may be a level sensor (not shown) coupled tothe storage vessel 440 and adapted to detect a metric indicative of thelevel of catalyst within the storage vessel 440. The level sensor may bean optical transducer, a capacitance device, a sonic transducer or otherdevice suitable for providing information from which the level or volumeof catalyst disposed in the storage vessel 440 may be resolved. Byutilizing sensed differences in the levels of catalyst disposed withinthe storage vessel 440 between dispenses, the amount of catalystinjected may be resolved for a known storage vessel geometry.

Alternatively, the sensor may be a flow sensor (not shown) adapted todetect the flow of catalyst through one of the components of thecatalyst injection system 402. The flow sensor maybe a contact ornon-contact device and may be mounted to the storage vessel 440 or thecatalyst delivery line 414 coupling the storage vessel 440 to thepressure vessel 420. For example, the flow sensor may be a sonic flowmeter or capacitance device adapted to detect the rate of entrainedparticles (i.e., catalyst) moving through the catalyst delivery line414.

Although the injection system 402 described above is shown configured toprovide catalyst from a single low pressure storage vessel 440, theinvention contemplates utilizing one or more injection systems coupledto the FCC unit 424 to introduce multiple catalysts from a plurality ofstorage vessels. Each of these injection systems may be controlled byeither common or independent control modules.

The pressure vessel 420 is rigidly coupled to the mounting surface 430,as load cells are not needed to determine the weight of the pressurevessel 420. The term “rigidly” is to include mounting devices, such asvibration dampers and the like, but to exclude mounting devices that“float” the pressure vessel to facilitate weight measurement thereof.The pressure vessel 420 has an operational pressure of about 0 to about100 pounds per square inch, and is coupled to a fluid source 406 by afirst conduit 418. The first conduit 418 includes a shut-off valve 416that selectively isolates the fluid source 406 from the pressure vessel420. A second conduit 422 couples the pressure vessel 420 to the FCCunit 424 and includes a second shut-off valve 426 that selectivelyisolates the pressure vessel 420 substantially from the FCC unit 424.The shut-off valves 416 and 426 are generally closed to allow thepressure vessel 420 to be filled with catalyst from the storage vessel440 at substantially atmospheric pressure.

Once the catalyst is dispensed into the pressure vessel 420, the controlvalve 432 is closed and the interior of the pressure vessel 420 ispressurized by a pressure control system 428 to a level that facilitatesinjection of the catalyst from the pressure vessel 420 into the FCC unit424, typically at least about 20 pounds per square inch. After theloaded pressure vessel 420 is pressurized by the pressure control system428, the shut-off valves 416 and 426 are opened, allowing air or otherfluid provided by the fluid source 406 to enter the pressure vessel 420through the first conduit 418 and carry the catalyst out of the pressurevessel 420 through the second conduit 422 to the FCC unit 424. In oneembodiment, the fluid source 406 provides air at about 60 to about 100psi (about 4.2 to about 7.0 kg/cm2).

In operation, the injection system 402 periodically dispenses andinjects a known quantity of catalyst into the FCC unit 424. Catalyst isfilled into the low pressure storage vessel 440 through the fill port442 located in an upper portion of the storage vessel 440. The weight ofthe storage vessel, including any catalyst residing therein, is obtainedby interpreting data obtained from the load cells 410.

In one embodiment, a predefined quantity of catalyst in the storagevessel 440 is transferred into the pressure vessel 420 by selectivelyopening the control valve 432 for a defined amount of time. After thecatalyst has been transferred, the weight of the storage vessel 440 isobtained once again, and the exact quantity of catalyst added determinedby subtracting the current weight from the previous measurement. Oncethe catalyst is transferred to the pressure vessel 420, the pressureinside the pressure vessel 420 is elevated by the pressure controlsystem 428 to, typically, at least about 20 psi. After operatingpressure is reached, valves 416 and 426 are opened. This allows fluidsupplied by the fluid source 406, typically air at approximately 60 psi,to flow through the pressure vessel 420 and carry the catalyst to theFCC unit 424.

This metering system is advantageous over the prior art in numerousrespects. For example, bulk storage of the catalyst at high pressure isnot required, thereby allowing the storage vessel 440 to be fabricatedless expensively as compared to pressurized bulk storage containers ofsome conventional systems. Furthermore, as the determination of theamount of catalyst being dispensed is made at the low pressure side ofthe system 402 (e.g., in the low pressure storage vessel or conduitbetween the storage vessel and pressure vessel), the pressure vessel 420does not need to be isolated by bellows in order to obtain catalystweight information, allowing for more accurate weight readings as wellas a more robust and less costly system.

FIG. 5 depicts another embodiment of a fluid catalytic cracking (FCC)system 500 comprising an injection system 502 and oil feed stock source450 coupled to an FCC unit 424. The injection system 502 is adapted toprovide multiple catalysts to the FCC unit 424. The injection system 502includes a control module 404 for controlling the rates and/or amountsof catalyst provided to the FCC unit 424 by the injection system 502, afluid handler 406 for injecting the catalyst into the FCC unit 424, anda pressure vessel 420 coupled to a plurality of storage vessels,illustratively shown in one embodiment as a first low pressure storagevessel 440 and a second low pressure storage vessel 510. It iscontemplated that any number of low pressure storage vessels may becoupled to a single pressure vessel 420 for injection catalyst at ahigher pressure.

The storage vessels 440, 510 may be configured to deliver the same ordifferent catalysts to the FCC unit 424 and operate substantiallysimilar to storage vessel 440, described above. The storage vessels 440,510 are coupled to a manifold 530 which directs the plurality ofcatalysts to a common catalyst delivery line 414 for delivery into thepressure vessel 420. Alternately, each storage vessel 440, 510 can beindependently coupled to the pressure vessel 420. Each storage vessel440, 510 is coupled to an independent metering device 432, 520 whichcontrols the amount of catalyst delivered from each storage vessel 440,510 to the pressure vessel 420 for injection into the FCC unit 424. Inone embodiment, the metering device 520 is configured similar to themetering device 432 described above. In this configuration, the system502 is capable of sequentially providing catalyst from a predefined oneof the storage vessels 440, 510, or alternatively, blending measuredamounts from each storage vessel 440, 510 in the pressure vessel 420 forinjecting into the FCC unit 424 in a single shot.

FIG. 6 depicts a flow diagram of one embodiment of a method 600 formetering catalyst in a FCC catalyst injection system. The method 600 isgenerally stored in the memory of the control module 404, typically as asoftware routine. The software routine may also be stored and/orexecuted by a second CPU (not shown) that is remotely located from thehardware being controlled by the control module 404. Although the method600 is discussed as being implemented as a software routine, some of themethod steps that are disclosed therein may be performed in hardware aswell as by the software controller, or manually. As such, the inventionmay be implemented in software as executed upon a computer system, inhardware as an application specific integrated circuit, or other type ofhardware implementation, manually, or a combination of software,hardware, and/or manual steps.

The method 600 begins at step 602 where the catalyst is metered from alow pressure storage vessel 440 to a pressure vessel 420. In this step,the metering and determination of catalyst transferred to the pressurevessel 420 is performed outside the pressure vessel 420 by the meteringdevice 408. For example, in the embodiment depicted in FIG. 4, step 602is performed by the combination of the metering device 408 and the loadcells 410 supporting the storage vessel 440 being utilized to determinethe amount of catalyst transferred to the pressure vessel 420. Thecatalyst is dispensed from the storage vessel 440 into the pressurevessel 420 by temporarily opening the control valve 432. The weight ofthe storage vessel 440 is measured both before and after dispensing thecatalyst by interpreting the output of the load cells 410 coupled to thelegs 438 which support the storage vessel 440. The amount of catalysttransferred to the pressure vessel 420 is the difference between theweight of the storage vessel 440 before and after dispensing thecatalyst. Alternatively, as discussed above, the catalyst meteringdevice 408 may be a shut-off valve, rotary valve, mass flow controller,pressure vessel, flow sensor, positive displacement pump, or otherdevice suitable for regulating the amount of catalyst dispensed from thestorage vessel 440 for delivery to the FCC unit 424.

At step 604, the pressure vessel 420 containing the catalyst ispressurized by the pressure control system 428 to between about 10 toabout 100 pounds per square inch. At step 606, the pressurized catalystis injected into the FCC unit 424. In this step, valves 416, 427 openwhich allow the catalyst to be carried to the FCC unit 424 in a streamof fluid provided by the fluid source 406. In the embodiment depicted inFIG. 4, the pressure vessel 420 is pressurized to at least about 10 psiby the pressure control system 428. Once the pressure has been reached,valves 416 and 426 are opened, allowing the fluid in the first andsecond conduits 418, 422 to carry the catalyst into the FCC unit 424.

FIG. 7 depicts a flow diagram of one embodiment of a method 700 formetering catalyst in a FCC catalyst injection system. The method 700begins at step 702 where a first catalyst is dispensed from a first lowpressure storage vessel 440 to a pressure vessel 420 using a meteringdevice 432, wherein the metering device determines the quantity of thefirst catalyst dispensed with respect to the first storage vessel. Atstep 704, the pressure vessel 420 containing the first catalyst ispressurized. Then, at step 706, the pressurized catalyst is injectedinto a FCC unit 424.

The method continues at step 708, where a second catalyst is meteredfrom a second low pressure storage vessel 510 to the pressure vessel 420using a metering device 520, wherein the metering device determines thequantity of the second catalyst dispensed with respect to the secondstorage vessel. At step 710, the pressure vessel 420 containing thesecond catalyst is pressurized and finally, at step 712, the pressurizedsecond catalyst is injected into the FCC unit 424. The method 700contemplates the use of additional low pressure vessel which load thepressure vessel 420 in a predefined order, or as needed.

FIG. 8 depicts a flow diagram of one embodiment of a method 800 formetering catalyst in a FCC catalyst injection system. In this method,beginning at step 802, a first catalyst is metered from a first lowpressure storage vessel 440 to a pressure vessel 420 using a meteringdevice 432, wherein the metering device determines the quantity of thefirst catalyst dispensed with respect to the first storage vessel. Atstep 804, a second catalyst is metered from a second low pressurestorage vessel 510 to the pressure vessel 420 using a metering device520, wherein the metering device determines the quantity of the secondcatalyst dispensed with respect to the second storage vessel. At step806, the pressure vessel 420 containing the first and second catalystsis pressurized and at step 808, the pressurized catalysts are injectedinto the FCC unit 424 as a single shot of catalyst. The method 800contemplates the use of additional low pressure vessels which mayprovide mixtures of different catalyst as needed or per a predefinedprocess sequence.

The methods described in FIGS. 7 and 8 allow for multiple catalysts tobe injected into the FCC unit as needed. For example, one catalyst maycontrol emissions from the cracking process and another catalyst maycontrol the resultant product mix produced by the FCC unit. This allowedgreater process flexibility with reduced capital expenditures.

Thus, an injection system has been provided that facilitates moreaccurate metering of catalyst and reduces problems associated withbellows used in some injection systems of the prior art. Moreover, theinventive system is compatible with existing low pressure storagevessels and does not require expensive bellows to isolate the pressurevessel. Therefore the inventive system is substantially less expensivethan the injection systems of the prior art.

Although the teachings of the present invention have been shown anddescribed in detail herein, those skilled in the art can readily deviseother varied embodiments that still incorporate the teachings and do notdepart from the scope and spirit of the invention.

1. Apparatus for loading catalyst to a fluid catalyst cracking unit,comprising: a pressure vessel having a single output adapted forcoupling to a fluid catalyst cracking unit; a plurality of separatecatalyst storage containers coupled to the vessel, the containersmaintained at a low pressure; and a pressure control system configuredto selectively pressurize the vessel to a high pressure.
 2. Theapparatus of claim 1 further comprising: at least one sensor configuredto provide a metric indicative of an amount of catalyst entering thevessel.
 3. The apparatus of claim 1 further comprising: at least oneload cell configured to provide a metric indicative of an amount ofcatalyst entering the vessel.
 4. Apparatus for loading catalyst to afluid catalyst cracking unit, comprising: an injection apparatus havingan outlet port for coupling to a fluid catalyst cracking unit (FCCU); aplurality of catalyst storage regions coupled to the injectionapparatus; and a change in weight measuring system interfaced with theinjection apparatus configured to determine an amount of catalystdelivered through the injection apparatus from a selected one of thecatalyst storage regions to the FCCU.
 5. The apparatus of claim 4further comprising: at least one load cell configured to provide ametric indicative of an amount of catalyst dispensed from a selected oneof the catalyst storage regions to the FCCU.